Impact of desflurane removal from the operating room on carbon dioxide emissions at a tertiary academic medical centre: a retrospective cohort study.

Abstract

Inhalational anaesthesia agents contribute to healthcare-related greenhouse gas emissions. We evaluated the carbon footprint of inhalation anaesthesia at a US academic medical centre over time and determined the relative importance of institutional measures (removal of desflurane and limiting fresh gas flow [FGF] and nitrous oxide [N₂O] use) to reduce carbon dioxide equivalent emissions (CO₂e-emissions). From 124 428 patients undergoing inhalational anaesthesia between 2014 and 2022, CO₂e-emissions per patient were calculated from minute-by-minute recordings of inspiratory concentrations of sevoflurane, isoflurane, desflurane, and N₂O, as well as FGF data. Data were combined with the global warming potential for each gas. Interrupted time series analysis, adjusted for patient and procedural factors, was applied to assess the impact of gradual removal of desflurane from operating rooms in June 2018 and its complete elimination in January 2020. From June 2014 to June 2022, mean CO₂e-emissions per patient decreased by 82.8% from an average of 83.1 (median, 23.6 [interquartile range, 10.1-107.8]) kg to 14.3 (median 8.5 [4.2-15.9]) kg. In adjusted analyses, restrictive use of desflurane (-1.53 kg per patient, 95% confidence interval, -1.88 to -1.18; P<0.001) and its subsequent elimination (additional -0.50 kg per patient, -0.80 to -0.19; P=0.002) reduced CO₂e-emissions. Before the elimination, desflurane was the main contributor to CO₂e-emissions (74% relative contribution). After the elimination, use of N₂O (73%) and high FGF (>3.42 L min^-1, 4%) emerged as dominant predictors of CO₂e-emissions. Eliminating desflurane led to a substantial reduction in anaesthesia-related CO₂e-emissions of ∼900 metric tonnes annually. This study highlights the importance of volatile anaesthetic choice and factors including N₂O use and fresh gas flow to minimise the carbon footprint of anaesthesia.